diff --git a/src/ccs.ts b/src/ccs.ts
index 1d5a7414..f5cb7486 100644
--- a/src/ccs.ts
+++ b/src/ccs.ts
@@ -611,6 +611,7 @@ async function main(): Promise<void> {
         isComposite: profileInfo.isComposite,
         compositeTiers: profileInfo.compositeTiers,
         compositeDefaultTier: profileInfo.compositeDefaultTier,
+        profileName: profileInfo.name,
       });
     } else if (profileInfo.type === 'copilot') {
       // COPILOT FLOW: GitHub Copilot subscription via copilot-api proxy
diff --git a/src/cliproxy/executor/index.ts b/src/cliproxy/executor/index.ts
index c5dbde93..0c6630e4 100644
--- a/src/cliproxy/executor/index.ts
+++ b/src/cliproxy/executor/index.ts
@@ -434,10 +434,11 @@ export async function execClaudeWithCLIProxy(
   if (forceConfig && supportsModelConfig(provider)) {
     // Block --config for composite variants (per-tier models in config.yaml)
     if (cfg.isComposite) {
+      const variantName = cfg.profileName || provider;
       console.log(
         warn('Composite variants use per-tier config. Edit config.yaml to change tier models.')
       );
-      console.error(`    Use "ccs cliproxy edit ${provider}" to modify composite variants`);
+      console.error(`    Use "ccs cliproxy edit ${variantName}" to modify composite variants`);
       process.exit(1);
     } else {
       await configureProviderModel(provider, true, cfg.customSettingsPath);
diff --git a/src/cliproxy/types.ts b/src/cliproxy/types.ts
index 06c83dc1..8db9142c 100644
--- a/src/cliproxy/types.ts
+++ b/src/cliproxy/types.ts
@@ -193,6 +193,8 @@ export interface ExecutorConfig {
   };
   /** Composite variant: which tier is the default */
   compositeDefaultTier?: 'opus' | 'sonnet' | 'haiku';
+  /** Original profile/variant name (e.g., "my-mix" for composite variants) */
+  profileName?: string;
 }
 
 /**
diff --git a/ui/src/components/cliproxy/cliproxy-edit-dialog.tsx b/ui/src/components/cliproxy/cliproxy-edit-dialog.tsx
index 9ac4a329..3197ebe1 100644
--- a/ui/src/components/cliproxy/cliproxy-edit-dialog.tsx
+++ b/ui/src/components/cliproxy/cliproxy-edit-dialog.tsx
@@ -90,16 +90,20 @@ export function CliproxyEditDialog({ variant, open, onOpenChange }: CliproxyEdit
     } else {
       singleForm.reset({
         provider: variant.provider,
-        model: variant.model || '',
-        account: variant.account || '',
+        model: variant.model ?? undefined,
+        account: variant.account ?? undefined,
       });
     }
   }, [variant, isComposite, singleForm, compositeForm]);
 
   const onSubmitSingle = async (data: SingleProviderFormData) => {
     if (!variant) return;
+    // Filter out undefined values - backend interprets undefined as "no change"
+    const payload = Object.fromEntries(
+      Object.entries(data).filter(([, v]) => v !== undefined && v !== '')
+    ) as SingleProviderFormData;
     try {
-      await updateMutation.mutateAsync({ name: variant.name, data });
+      await updateMutation.mutateAsync({ name: variant.name, data: payload });
       onOpenChange(false);
     } catch (error) {
       console.error('Failed to update variant:', error);